The Hitachi 200 KeV analytical electron microscope can now produce EELS elemental maps of the low Z elements, carbon, nitrogen and oxygen, which constitute most of the mass of a cell. Since the relative numbers of these atoms vary from one cellular compartment to another, significant information should be contained in C, N and O images. In order to learn how low Z imaging can be applied to cell physiology, carbon and nitrogen maps have been obtained from the well characterized bovine adrenal chromaffin cells. In particular the secretory granules, which are important in the production and exocytosis of epinephrine, have been imaged for nitrogen and carbon. The granules are shown to rich in nitrogen, probably due largely to nucleotides, but some nitrogen deficient regions are evident which can be correlated with membrane-bound compartments in the STEM micrographs. The granule membranes are apparent in the carbon image. It is intended to extend the study to cells which have been treated with fluorine labeled catecholamines. Detection of fluorine would greatly extend the usefulness of the method.